Technical Field
The present disclosure relates to a compensation structure for a torque wrench, more particularly relates to a spring compensation structure for a torque wrench.
Description of Related Art
Mechanical parts are becoming more delicate and complicated with the advance of mechanical manufacturing technology. The knowledge on mechanical assembling is also continuingly raising for the people. Not only a machine factory, demand on applying a precise torque to a component is increased for the people who repair by themselves household goods, leisure equipment or vehicles. As such, requirements on the precision of a tongue wrench are increasingly high.
The torque wrench is a precision hand tool that can obtain a required torque while engaging with a component. Conventional torque wrench utilizes a spring as a torque sensor; when a torque of the torque wrench reaches a specified value, a deformation of the spring reaches to a specified value simultaneously. Some of the conventional torque wrenches utilize a trip mechanism for tripping to make a warning sound, and the other ones utilize a display or an indicator to show the torque value or a warning signal when the spring is force taken and deformed.
FIG. 1 is a structural diagram showing a structure of a conventional torque wrench. The torque wrench includes a body 100 and an engaging head 500. The engaging head 500 is located at one end of the body 100 for connecting and applying a torque to a workpiece. The body 100 includes a spring 101 located inside and connected with the engaging head 500. A handle portion 102 is located at outside of the body 100 for gripping with a user. A sensor 103 is connected with the spring 101 for sensing and converting the force taken on the spring 101 to a torque value, and the torque value is displayed on a display panel (not shown).
When the elasticity of the spring is gradually decreased after the use for a period of time, using frequency or using strength, the accuracy of the torque wrench is decreased accordingly. Therefore, the torque value is no longer accurate, and the torque wrench is no longer being useful.
For saving the cost of replacing a new torque wrench, a new kind torque wrench with a calibratable torque value has been developed. When the spring of a torque wrench losses elasticity but other components of the torque wrench work, one conventional method is provided to open the torque wrench and replace the used spring to a new one in order to recover the accuracy of the torque wrench. Another conventional method is provided to add an extra gasket incorporated with the spring for increasing a pre-compression of the spring in order to compensate the elastic fatigue. Some other conventional method is to open the torque wrench and adjust the position of the spring in order to increase the pre-compression of the spring thereby to compensate the elastic fatigue.
However, the conventional methods described above suffer from a shortcoming that opening the torque wrench is required to conduct an adjustment. Therefore, the methods are very complicated in process steps and may have great influences on the original setting of the components of the torque wrench, thereby leading more difficulty on assembly and calibration of the components. Moreover, since the conventional spring compensation structure has to be maintained directly from the inner structure of the torque wrench, the components involved complicated and the operation in the maintenance is highly precisely. As a result, the manufacturing process is difficult and the cost of the torque wrench keeps high.